Bitcoin
ownership,
zero knowledge.
Prove you hold Bitcoin — without revealing your address.
ZK proofs generated entirely in your browser. Verified on Starknet.
The Problem
Proving Bitcoin ownership
costs you your privacy.
Every time you prove you hold Bitcoin — for KYC, DeFi collateral, DAO voting, or trust — you hand over your address. That means your entire transaction history, your balance, and every wallet you've ever touched.
Your address reveals everything
A Bitcoin address is a permanent public record. Share it once and anyone can trace every transaction you've ever made — past, present, and future.
Status quoProve the fact, not the address
With Privex you prove "I hold ≥ 0.5 BTC since block 850,000" using a ZK proof. The verifier learns only that — nothing else about you.
With PrivexBalance exposed on explorers
Traditional proof requires a signed message from your address — permanently linking your identity to your exact holdings on every public explorer.
Status quoOnly the threshold hits the chain
The on-chain record shows threshold, ZK commitment, and your chosen username. Actual balance, address, and history stay entirely off-chain.
With PrivexHow It Works
Four steps.
Fully in your browser.
No backend. No server. No private key transmission. Everything from proof generation to on-chain settlement happens client-side using Noir circuits compiled to WASM.
Fetch UTXOs
Your Bitcoin address fetches UTXO data from mempool.space locally. Block headers are retrieved to anchor timestamps on-chain.
Generate ZK Proof
A Noir circuit runs in your browser via bb.js WASM. It proves balance ≥ threshold and historical ownership — exposing no private inputs.
Encode Calldata
Garaga transforms the UltraKeccakZKHonk proof into Starknet calldata — the exact format the on-chain verifier contract expects.
Verify On-Chain
Your wallet submits the proof to the router. The Garaga verifier confirms it. The result is permanent, public, and trustless.
Who Uses Privex
Built for anyone who needs
to prove without exposing.
From DeFi protocols to private individuals, the ability to prove Bitcoin ownership without disclosure has wide and growing applications across the ecosystem.
DeFi Collateral
Unlock lending, borrowing, or yield positions on Starknet by proving BTC holdings — without bridging assets or revealing your wallet address.
DAO Governance
Gate voting rights by Bitcoin holdings. Members prove their stake without doxxing their address to the DAO or any public record.
OTC Trust
Establish credibility in peer-to-peer deals. Share a signed ZK certificate — not your address — to prove you have the funds.
Token-Gated Access
Restrict access to communities or content to verified Bitcoin holders — without storing any wallet address on record.
Compliance
Satisfy proof-of-funds requirements without full financial disclosure. Demonstrate sufficiency to a threshold — nothing beyond that.
Personal Privacy
Prove long-term holding. Establish credibility anywhere. Your history is yours — Privex lets you decide exactly what to reveal.
The Stack
Production-grade cryptography,
assembled carefully.
Every component was chosen for correctness and composability. The proof system is fully open — circuits, contracts, and calldata encoding are all auditable.
ZK circuit language. Three circuits: balance threshold, multi-address combined balance, and historical ownership with 8-header Bitcoin chain verification.
Barretenberg WASM backend. Runs UltraKeccakZKHonk proving entirely in the browser. No server-side computation required at any step.
Proof encoding library for Starknet. Converts UltraKeccakZKHonk proofs into the calldata format expected by deployed Cairo verifier contracts.
L2 settlement. The router contract dispatches proofs to Garaga-generated type-specific verifiers. Results are permanent and publicly auditable.
Get Started
Your proof,
your terms.
Generate a ZK proof of your Bitcoin holdings in minutes. Nothing leaves your browser until you choose to submit.